1. Field Of The Invention
The present invention relates to the field of computer display systems. Specifically, the present invention pertains to the manipulation and control of graphics and video data for display on a display medium. The present invention further relates to the control and manipulation of audio data that is output in synchronization with images on a display screen.
2. Prior Art
Many conventional computer graphics display systems exist in the prior art. These systems provide mechanisms for manipulating and displaying graphics objects on a display screen. These graphic objects include points, vectors, conical shapes, rectangles, polygons, arcs, alpha numeric information, shaded or color-filled regions, and other forms of graphic imagery, typically represented as objects in a two dimensional or three dimensional virtual space. A graphics computer program in these conventional systems provides mechanisms by which a computer user may manipulate graphic objects using functions provided by the graphics software. This graphics software typically includes a graphics driver software module that operates in conjunction with a graphics controller to load a frame buffer with digital information that is subsequently converted to a form displayable on a display screen. It will be apparent to those skilled in the art that the use of graphics driver software, graphics controllers, and frame buffers is well known to those of ordinary skill in the art.
Other prior art computer display systems provide a means for displaying video images on a display screen. These video images comprise streams of digital video data encoded in several well known formats such as MPEG, JPEG, and RTV format. Unlike graphical data, this video data includes no representations of individual objects within the video image. To the computer display system, the video image is a homogeneous video data stream encoded in a particular way. In prior art systems, this video data is received by processing logic that includes a particular mechanism for decoding the video data and transferring the decoded video data into a frame buffer for display on the display screen. Because of the different nature of graphical data as compared with video data, prior art systems tend to handle graphical and video data in separate subsystems within the computer display system. Thus, graphical data and video data typically take parallel and independent paths through prior art systems as the data is processed for display. In some cases, two separate frame buffers are used, one for graphical data and one for video data. In other systems, a single frame buffer is used; however, graphical data occupies one distinct region of the frame buffer and video data occupies a different portion of the frame buffer.
A number of problems exist in prior art systems that process graphical and video data independently. First, these prior art systems cannot efficiently combine graphical and video images together into a composite form that is easily manipulated. For example, scrolling a graphical image across a video background typically requires additional processing to prevent image from being destroyed. Secondly, synchronizing graphics and video images in prior art systems is typically very difficult. Synchronization problems in prior art systems result in video images that appear tom or disjoint. Moreover, aligning graphics images at the proper location and time in a video image is difficult using prior art techniques. Thirdly, the video data decoding schemes used in prior art systems are typically limited to a single decoding scheme. For example, less expensive graphics programs may provide software implemented video data decoders. Although these systems provide an inexpensive solution, they tend to run slowly and often provide decoded video data of a low resolution. Other more expensive prior art systems provide graphics hardware that may be used to decode a video data stream. These systems are fast and provide high resolution decoded video data; however, they are also substantially more expensive. Moreover, users wanting to upgrade from a less expensive system, such as a software implemented decoder, to a more expensive system, such as a graphic hardware implemented system, must first reconfigure or reinstall their graphics application program in order to take advantage of a different video decoding technique. This additional impact at the applications program level further increases the upgrade cost to the computer user.
Thus, a better means for integrating graphical and video information in a single computer display system is needed.